Question

Giúp giải chi tiết vs ạ

Answer 1

Bài 2:

a. 8x(5x - 2) - 12(5x - 2) = 0

<=> (8x - 12)(5x - 2) = 0

<=> \(\left[{}\begin{matrix}8x-12=0\\5x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=\dfrac{5}{2}\end{matrix}\right.\)

Answer 2

Bài 1 

a)2x(5x-2)+(2x+1)(8-5x)
=10x^2-4x+16x-10x^2+8-5x

=7x+8

Answer 3

b)(x+7)(x-7)-(x-3)^2

=x^2-49-(x^2-6x+9)

=6x-40

Answer 4

bài 2 

b) 8x(5x-2)-12(5x-2)=0

(8x-12)(5x-2)           =0

⇔8x-12                   =0  ⇔8x=12⇔x=3/2

⇔5x-2                     =0  ⇔5x=2⇔x=2/5